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Homework Help: A solid ball problem

  1. Oct 27, 2004 #1
    Here is my last problem I am having problems with:
    A solid ball of mass 1.70kg and diameter 16.0cm is rotating about its diameter at 65.0rev/min. What is its kinetic energy ?
    Ok so KE for rotation is : 1/2*I *w^2
    so I found I with m *r2
    and then plugged everthing into the Ke equation but didnt get it right. I converted everything and divided the diameter by 2. What could I be doing wrong??
  2. jcsd
  3. Oct 27, 2004 #2


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    Science Advisor
    Homework Helper

    Check your moment of inertia for a sphere!
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